(1) Field of the Invention
This invention relates a crosslinking vinyl chloride resin plastisol. More particularly, it relates to a crosslinking vinyl chloride resin plastisol used as a paste vinyl chloride resin for shaped articles and laminated articles, which has good heat distortion resistance, chemical resistance, resistance to whitening due to water, adhesion and thermal resistance on processing.
(2) Description of the Related Art
Laminated articles having a laminate structure comprised of a shaped article and a surface protective layer of a vinyl chloride resin (said layer may be hereinafter called as "top layer"), formed on the shaped article, have heretofore been widely used, wherein the shaped articles include, for example, (1) a shaped article made of a synthetic resin such as a vinyl chloride resin or polyurethane, (2) a steel plate or sheet, an aluminum foil, a metal plate or sheet, plaster, a wooden article, or paper, (3) a printed article having a printed image formed on a substrate such as exemplified in the above (2), and (4) an organic or inorganic fibrous or textile article.
As typical examples of such laminated articles, there can be mentioned floorings, (1) wall materials and cushioning materials, which have a foamed substrate made of a vinyl chloride resin or polyurethane, (2) a metal plate or sheet having a surface protective or decorative layer, and (3) flat articles which are comprised of a sheet-form material made of nylon, a polyester resin, a glass fiber or paper, and a surface coating of a vinyl chloride resin.
The formation of a top layer on various shaped articles is intended to give some physical and chemical properties to the shaped articles, such as tenacity, abrasion resistance, chemical resistance, resistance to whitening due to water (i.e., resistance to whitening or loss of transparency due to water-absorption or moisture-absorption), and flame retardancy, whereby the shaped articles are protected to enhance the practical performance, or a decorative effect is given to the shaped articles to enhance the commercial value.
Thus, a vinyl chloride resin is laminated on shaped articles to obtain a protective or decorative effect. However, a vinyl chloride resin is thermoplastic and is incorporated with a plasticizer in view of hand and feeling in the field of the above-listed laminated articles. Therefore the vinyl chloride-coated articles have a problem such that the softening point is low and the thermal resistance is poor.
To solve this problem, attempts have been made to crosslink a vinyl chloride resin. A typical example of the crosslinking of a vinyl chloride resin is effected by using a triazine compound (Japanese Examined Patent Publication No. 54-42390 and Japanese Examined Patent Publication No. 55-6501). The crosslinked vinyl chloride resin crosslinked with a triazine compound has improved thermal resistance, chemical resistance and abrasion resistance, but the resistance to whitening due to water and the thermal stability upon processing are drastically lowered. Therefore, the use of such a crosslinked vinyl chloride resin is limited and is used only in certain shaped articles, even though it is desirable to use a crosslinked vinyl chloride resin in wide fields.
The formation of a vinyl chloride resin top layer on a shaped article is carried out by a procedure wherein a vinyl chloride resin is directly coated on a shaped article, or a procedure wherein an adhesive is previously coated on a shaped article and then a vinyl chloride resin layer is adhered thereon. The latter procedure is not advantageous in that a step of coating with an adhesive and a step of drying the coated adhesive are indispensable. A procedure has been proposed wherein an isocyanate adhesive is incorporated in a vinyl chloride resin sol and the sol is coated on a shaped article. This procedure can be applied only for shaped articles made of nylon or a polyester.